Plate heat exchangers typically consist of two end plates in between which a number of heat transfer plates are arranged in an aligned manner. In one type of well-known PHEs, the so called gasketed plate heat exchangers, gaskets are arranged between the heat transfer plates. The end plates, and therefore the heat transfer plates, are pressed towards each other whereby the gaskets seal between the heat transfer plates. The gaskets define parallel flow channels between the heat transfer plates through which channels two fluids of initially different temperatures alternately can flow for transferring heat from one fluid to the other.
The fluids enter and exit the channels through inlet and outlet ports, respectively, which extend through the plate heat exchanger and are formed by respective aligned port holes in the heat transfer plates. The inlet and outlet ports communicate with inlets and outlets, respectively, of the plate heat exchanger. Equipment like pumps is required for feeding the two fluids through the plate heat exchanger. The smaller the inlet and outlet ports are, the larger the pressure drop of the fluids inside the PHE gets and the more powerful, and thus expensive, equipment is required for proper operation of the PHE. Naturally, the diameter of the inlet and outlet ports could be made larger in order to decrease the pressure drop of the fluids and enable use of less powerful equipment. However, enlarging the diameter of the inlet and outlet ports means increasing the diameter of the of the port holes in the heat transfer plates. In turn, this could result in that valuable heat transfer surface of the heat transfer plate must be sacrificed which is typically associated with a lowered heat transfer efficiency of the plate heat exchanger.